Code isn't running through

So I'm trying to make a Ahem Potato say something when the Player enters the Trigger and Left clicks on the Potato Game object (all of this is 2D). The Potato will ask a question and depending on the answer from the player the Potato will respond appropriately, and after the player answers the question the Potato will not ask any more questions as it marks as has talked to.

BUT

I have run into a problem the Potato won't talk when clicked on. The Potato game object is 0 on the Z axis and is set to trigger. I'm using C# and for the Life of me I cannot find out why. If you take time to fix this please explain what was wrong as I like to learn from mistakes.

 using UnityEngine;
 using System.Collections;
 
 public class ProtatoTalk : MonoBehaviour {
     public string [] answerButton;
     public string [] Questions; 
     bool DisplayDialog = false; 
     bool HasTalkedTo = false; 
 
     void onGUI()
     {
         GUILayout.BeginArea (new Rect (1, 1, 400, 400)); 
         if (DisplayDialog && !HasTalkedTo) 
     {
 
             GUILayout.Label(Questions[0]);
             if(GUILayout.Button (answerButton[0]))
             {
                 GUILayout.Label (Questions[1]);
                 HasTalkedTo = true; 
             }
 
             if(GUILayout.Button (answerButton[1]))
             {
                 GUILayout.Label (Questions[2]);
                 HasTalkedTo = true;
             }
 
     }
         GUILayout.Label (Questions[3]); 
         GUILayout.EndArea(); 
     }
     
         void OnTriggerEnter()
     {
         if(Input.GetMouseButtonDown(0))
             DisplayDialog = true; 
     }
 
     
         void OnTriggerExit()
     {
         DisplayDialog = false;
     }
 }